Back in days of yore when I was in high school and we had a closed circuit TV studio for teaching, I used the technique of focusing with the lens zoomed in all the way, then the lens would maintain focus when I zoomed out. That was not an autofocus camera or lens.

With an autofocus camera, unless for some reason you're turning off the autofocus function, the question is academic, since the camera will refocus at whatever zoom setting you use. But I suspect that most modern still camera zoom lenses aren't designed to maintain focus the same way that TV camera lens did.
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--Bob